1. Field of the Invention
The invention concerns a bearing shell for heavily loaded bearings operating in an abrasive environment comprising a generally annular body with an axial bore provided with a lining in which a shaft turns in contact with a bearing surface of the lining.
2. Description of the Prior Art
Various sectors of mechanical engineering require bearings which are relatively undemanding in terms of rotation speed or precision but are of rugged construction and must have:
a) good resistance to wear, especially abrasive wear (for example in contact with rust or mud); PA1 b) good load capacity and ability to withstand dynamic overloads and impacts; PA1 c) good friction characteristics (silent operation, requiring lubrication only at assembly time); and PA1 d) good corrosion resistance to withstand contact with water or salt spray.
Examples:
In the civil engineering sector, bearings for mechanical diggers, loaders, bucket conveyors, piston pump connecting rod small-end bearings;
In the iron and steel sector, chain transfer conveyor bearings, mold closure hinge bearings, bogie hearth furnace wheel bearings;
In the agricultural machinery sector, machine bearings, tractor front axle kingpins;
In the goods vehicle sector, suspension spring and brake linkage bearings.
Conventional bearings such as ball bearings and roller bearings designed for high rotation speeds are too costly for applications of the kind just mentioned, especially as the loads involved would require them to be highly rated and they would have to be housed in sealed enclosures to protect them from abrasion and corrosion, which would further increase the cost.
Bearings lined with relatively soft metals such as bronze and white metal are not able to withstand abrasive surroundings or high loads.
Surface-hardened steels provide a better solution to the production of bearings of the kind mentioned above; this is especially so if the surface treatment improves corrosion resistance and the coefficient of friction. Surface treatment is relatively costly, however, especially if it is restricted to the bearing surface. Also, performance under load is not so good as would be desirable.